Investments (Summary of Realized Gain (Loss) on Investments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Investments [Line Items]
Gain (loss) on investments	$ 2,501	$ 74
Unrealized gain on other investments	(441)
Other-than-temporary impairment		(301)
Net realized (losses) gains	2,060	(227)
Other Investments [Member]
Schedule of Investments [Line Items]
Gain (loss) on investments
Us Treasury Securities and Obligations of U.S. Government [Member]
Schedule of Investments [Line Items]
Gain (loss) on investments
Corporate Bonds [Member]
Schedule of Investments [Line Items]
Gain (loss) on investments	130	80
Collateralized Corporate Bank Loans [Member]
Schedule of Investments [Line Items]
Gain (loss) on investments	28	18
Municipal Bonds [Member]
Schedule of Investments [Line Items]
Gain (loss) on investments	(17)	$ (24)
Equity Securities [Member]
Schedule of Investments [Line Items]
Gain (loss) on investments	$ 2,360